POS0745 THE INCIDENCE AND PREVALENCE OF JUVENILE IDIOPATHIC ARTHRITIS DIFFERS BETWEEN ETHNIC GROUPS IN ENGLAND
Authors: R. Beesley, K. Hyrich, J. Humphreys
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Juvenile Idiopathic Arthritis (JIA) is a heterogenous group of autoimmune disorders characterised by chronic joint inflammation, affecting children and young people (CYP) under the age of 16. Recent analysis in the UK has updated estimates of the incidence and prevalence of JIA, but the association between ethnicity and JIA has not been investigated in the UK context. Differential rates between ethnic groups could be indicative of underlying biological differences and/or health inequities. Health inequities (avoidable systemic differences in health outcomes for different population groups) may lead to specific ethnic groups being less likely to be referred resulting in delays in diagnosis and apparent differences in incidence rates. <h3>Objectives</h3> To calculate and compare the incidence and prevalence rates of JIA in different ethnic groups in England. <h3>Methods</h3> CYP with JIA were identified in anonymised electronic primary care records (the Clinical Practice Research Datalink (CPRD) Aurum database) using pre-defined read code lists between 1995 and 2011. Cases were further validated through linked Hospital Episode Statistics (HES) data with either &gt;=3 outpatient specialist care (rheumatology/paediatric rheumatology) appointments or a HES inpatient admission coded with JIA, prior to age 16. Ethnic group was extracted from CPRD/HES records and aggregated to broad ethnic groups, as defined by the Office for National Statistics (ONS). Incidence and prevalence rates by broad ethnic group were calculated using CYP under the age of 16 in CPRD, as of December 2011. Indirect standardisation was performed by age and region using ONS Census 2011 data, to account for varying ethnic make-up across different age groups and regions of England. The distribution of observed JIA cases across ethnic groups was subsequently compared with the expected distribution based on population statistics using Chi2. <h3>Results</h3> A total of 314 incident cases were identified in CYP &lt;16y between January 1995 and December 2011 using code lists. The overall age and region indirectly standardised incidence rate was 4.3 per 100,000 population age &lt;16y, varying from 4.7 for White CYP to 1.1 for CYP with Mixed ethnic group. A total of 268 HES-validated cases were identified, giving an indirectly standardised incident rate of 4.3 per 100,000 population age &lt;16y, varying from 4.8 for White CYP to 0.9 for CYP with Mixed ethnic group. In December 2011 there were 471 prevalent cases from code lists (381 validated using HES). The indirectly standardised prevalence rate was 35 per 100,000 CYP under the age of 16 (31 for validated cases), varying from 38 (34) for White CYP to 11 (11) for CYP with Mixed ethnic group. <h3>Conclusion</h3> The incidence and prevalence of JIA amongst CYP in England differs by ethnic group, being highest amongst 'White' CYP and lower amongst other ethnic groups, and is not in keeping with the known distribution of ethnic groups in the &lt;16y England population. Understanding whether this reflects a health inequity or differences in the underlying biology of JIA needs further evaluation. <h3>REFERENCES:</h3> NIL. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.